Interstellar gas, which is an important ingredient of galaxies, fills the space in between the star system in a galaxy. It is composed of multiple phases and has a wide range of physical conditions. Stars form within the densest regions of interstellar gas, and newly born stars impart radiational and kinematical feedback to the ambient gas. As well as the stellar feedback, various interstellar processes such as supernova explosions and gravitational interactions with massive objects can imprint on the distribution, kinematics, and physical conditions of interstellar gas [1]}, [2]}.
